Speed of boat in still water = x kmph. Speed of current = y kmph. Rate downstream = (x + y) kmph Rate upstream = (x – y) kmph. According to the question, x+y=
20
1
40
60
kmph ⇒x+y=
20
5
3
=
20×3
5
= 12 kmph ....(i) ∴
2×20
x+y
=
20
x−y
⇒ 2x – 2y = x + y ⇒ x = 3y .....(ii) From equation (i), 3y + y = 12 ⇒ 4y = 12 ⇒ y =